Make bulk loading into Cassandra less crappy, more pluggable

Details

Description

Currently bulk loading into Cassandra is a black art. People are either directed to just do it responsibly with thrift or a higher level client, or they have to explore the contrib/bmt example - http://wiki.apache.org/cassandra/BinaryMemtable That contrib module requires delving into the code to find out how it works and then applying it to the given problem. Using either method, the user also needs to keep in mind that overloading the cluster is possible - which will hopefully be addressed in CASSANDRA-685

This improvement would be to create a contrib module or set of documents dealing with bulk loading. Perhaps it could include code in the Core to make it more pluggable for external clients of different types.

It is just that this is something that many that are new to Cassandra need to do - bulk load their data into Cassandra.